package cn.zswltech.gruul.web.api.util;

import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.nio.charset.Charset;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

/**
 * <p>
 * RSA公钥/私钥/签名工具包
 * </p>
 * <p>
 * 罗纳德·李维斯特（Ron [R]ivest）、阿迪·萨莫尔（Adi [S]hamir）和伦纳德·阿德曼（Leonard [A]dleman）
 * </p>
 * <p>
 * 字符串格式的密钥在未在特殊说明情况下都为BASE64编码格式<br/>
 * 由于非对称加密速度极其缓慢，一般文件不使用它来加密而是使用对称加密，<br/>
 * 非对称加密算法可以用来对对称加密的密钥加密，这样保证密钥的安全也就保证了数据的安全
 * </p>
 *
 * @author IceWee
 * @version 1.0
 * @date 2012-4-26
 */
public class RSAUtils {

    /**
     * 加密算法RSA
     */
    public static final String KEY_ALGORITHM = "RSA";

    /**
     * 签名算法
     */
    public static final String SIGNATURE_ALGORITHM = "MD5withRSA";

    /**
     * 获取公钥的key
     */
    private static final String PUBLIC_KEY = "RSAPublicKey";

    /**
     * 获取私钥的key
     */
    private static final String PRIVATE_KEY = "RSAPrivateKey";

    /**
     * RSA最大加密明文大小
     */
    private static final int MAX_ENCRYPT_BLOCK = 117;

    /**
     * RSA最大解密密文大小
     */
    private static final int MAX_DECRYPT_BLOCK = 128;

    /**
     * <p>
     * 生成密钥对(公钥和私钥)
     * </p>
     *
     * @return
     * @throws Exception
     */
    public static Map<String, Object> genKeyPair() throws Exception {
        KeyPairGenerator keyPairGen = KeyPairGenerator
                .getInstance(KEY_ALGORITHM);
        keyPairGen.initialize(1024);
        KeyPair keyPair = keyPairGen.generateKeyPair();
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
        Map<String, Object> keyMap = new HashMap<String, Object>(2);
        keyMap.put(PUBLIC_KEY, publicKey);
        keyMap.put(PRIVATE_KEY, privateKey);
        return keyMap;
    }

    /**
     * <p>
     * 用私钥对信息生成数字签名
     * </p>
     *
     * @param data       已加密数据
     * @param privateKey 私钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static String sign(byte[] data, String privateKey) throws Exception {
        byte[] keyBytes = Base64Utils.decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PrivateKey privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initSign(privateK);
        signature.update(data);
        return Base64Utils.encode(signature.sign());
    }

    /**
     * <p>
     * 校验数字签名
     * </p>
     *
     * @param data      已加密数据
     * @param publicKey 公钥(BASE64编码)
     * @param sign      数字签名
     * @return
     * @throws Exception
     */
    public static boolean verify(byte[] data, String publicKey, String sign)
            throws Exception {
        byte[] keyBytes = Base64Utils.decode(publicKey);
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PublicKey publicK = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initVerify(publicK);
        signature.update(data);
        return signature.verify(Base64Utils.decode(sign));
    }

    /**
     * <P>
     * 私钥解密
     * </p>
     *
     * @param encryptedData 已加密数据
     * @param privateKey    私钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPrivateKey(byte[] encryptedData,
                                             String privateKey) throws Exception {
        byte[] keyBytes = Base64Utils.decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, privateK);
        int inputLen = encryptedData.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段解密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher
                        .doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher
                        .doFinal(encryptedData, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        return decryptedData;
    }

    /**
     * <p>
     * 公钥解密
     * </p>
     *
     * @param encryptedData 已加密数据
     * @param publicKey     公钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPublicKey(byte[] encryptedData, String publicKey) throws Exception {
        publicKey = handleKey(publicKey);
        byte[] keyBytes = Base64Utils.decode(publicKey);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicK = keyFactory.generatePublic(x509KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, publicK);
        int inputLen = encryptedData.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段解密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher
                        .doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher
                        .doFinal(encryptedData, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        return decryptedData;
    }

    /**
     * <p>
     * 公钥加密
     * </p>
     *
     * @param data      源数据
     * @param publicKey 公钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPublicKey(byte[] data, String publicKey)
            throws Exception {
        byte[] keyBytes = Base64Utils.decode(publicKey);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicK = keyFactory.generatePublic(x509KeySpec);
        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, publicK);
        int inputLen = data.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段加密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        return encryptedData;
    }

    /**
     * <p>
     * 私钥加密
     * </p>
     *
     * @param data       源数据
     * @param privateKey 私钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPrivateKey(byte[] data, String privateKey) throws Exception {
        privateKey = handleKey(privateKey);
        byte[] keyBytes = Base64Utils.decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, privateK);
        int inputLen = data.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段加密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        return encryptedData;
    }

    /**
     * <p>
     * 获取私钥
     * </p>
     *
     * @param keyMap 密钥对
     * @return
     * @throws Exception
     */
    public static String getPrivateKey(Map<String, Object> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PRIVATE_KEY);
        return Base64Utils.encode(key.getEncoded());
    }

    /**
     * <p>
     * 获取公钥
     * </p>
     *
     * @param keyMap 密钥对
     * @return
     * @throws Exception
     */
    public static String getPublicKey(Map<String, Object> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PUBLIC_KEY);
        return Base64Utils.encode(key.getEncoded());
    }

    private static String handleKey(String key) {
        return key.substring(key.indexOf("\n"), key.lastIndexOf(("\n"))).replaceAll("\t", "");
    }

    public static void main(String[] args) throws Exception {
        String privateKey = "-----BEGIN PRIVATE KEY-----\n" +
                "MIICeQIBADANBgkqhkiG9w0BAQEFAASCAmMwggJfAgEAAoGBAO3Tmap3hNgs/BqF\n" +
                "xGczzChkjVDj69NxMQibUK++CLsXE877Pgjsx55MkKqrHPER5mTl7VCCeRwoidFk\n" +
                "B1WaVFPce7HHaC6HdgDOGPZjixKx01Oq8nAqb5YaVWJ8a7WFNDvDC+d/lxhmjl/U\n" +
                "WPXtIMJH6SVj8UstIQyXVRn/kQXrAgMBAAECgYEAyu5gU52yRAd2gmcb5HfFP740\n" +
                "+w3QX1ZZYZ+tpJfBuWqCo32sPE9WMZPhaU+i3WzJq9Spv6XlE4rftkTlIT0Tr+nX\n" +
                "JniBtNsRpN1zAIDOnGMhZ0kSMvcCgYbh8daEhgTxejDjJ2h22RUFYnmbEBIbPwKo\n" +
                "ois2XXkCOGfoDZ/B+xECQQD9hDAM0lgO0NoVWLNSumCykFLgDn4ovvVB8yuf5JTT\n" +
                "n7mwFtE7h4eNCga+Uvt4Np/CPbYrfzve/7B5ib9m7f4TAkEA8CgQHvpAhzgE8hNw\n" +
                "FLcNvTjbSc9iyVWB8VcSsH7+s2LXjPmLY2UwJ/mpyPmdbb6BzoTqul48Aa0qpaxP\n" +
                "DmZzyQJBANTGhoGsZYYB2phB+zf6/7+/DB/Lai2OoFA65Sls81Bu5a2aaP/6r1U7\n" +
                "zg8dnLv3tLyViPkW78wpdBd9+mxMYYsCQQCH/be7Qux9ZXxvdBBYupueFe8fKb9/\n" +
                "0NrHRg5AQXmLLSJwIvMKcsdFK7w4IRlDhshMoLmmlSwXqu5maF9QATX5AkEA8pDy\n" +
                "HIRywbgHCNiyU2YK0jerXsi+52tX4QuypW3pH9XPDXspl4QBH9m+KbzhVtZQ0Xk4\n" +
                "iKlEiSiwT8OgJjAJPw==\n" +
                "-----END PRIVATE KEY-----";
        String publicKey = "-----BEGIN PUBLIC KEY-----\n" +
                "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDt05mqd4TYLPwahcRnM8woZI1Q\n" +
                "4+vTcTEIm1Cvvgi7FxPO+z4I7MeeTJCqqxzxEeZk5e1QgnkcKInRZAdVmlRT3Hux\n" +
                "x2guh3YAzhj2Y4sSsdNTqvJwKm+WGlVifGu1hTQ7wwvnf5cYZo5f1Fj17SDCR+kl\n" +
                "Y/FLLSEMl1UZ/5EF6wIDAQAB\n" +
                "-----END PUBLIC KEY-----";
        //测试字符串
        String data = "123456";
        //加密
        String entryData = Base64Utils.encode(RSAUtils.encryptByPrivateKey(data.getBytes(Charset.defaultCharset()), privateKey));
        System.out.println("entryData：\n" + entryData);
//            String entryData = "6w4eNXen1i/lhm/tHzjbQjXqpNFdoL6wTvFkgtzeP/4jkhupFlcDF0Hx/ZA53T/3BzVFr7bO5djaiMeg6v42yRc4fGdDk5+WHjjw7vCdXwZsNtZoYlyQld8AzLu6ZjPbQ59PXB0tzCocCjtlOyKfGuUfAnR2rkL/Dq0JKHwVxio=";
        //解密
        data = new String(RSAUtils.decryptByPublicKey(Base64Utils.decode(entryData), publicKey), Charset.defaultCharset());
        System.out.println(new String(data));
    }

}
